Image control means and structured transfer sheet for thermal reproduction processes

Abstract

A transfer sheet for thermal reproduction processes having a discontinuous transfer layer defined by a plurality of closely spaced discrete carbon regions. In a specific embodiment the transfer surface is defined by a substantially uniform distribution of carbon regions of varying diameters providing improved continuous tone reproduction through temperature-correlated carbon transfer.

We claim: 
     
       1. In the combination of a transfer sheet comprising a substrate and a thermally transferable heat-sensitive material thereon, and a master sheet for receiving said heat-sensitive material by thermal transfer from said transfer sheet, the improvement wherein said heat-sensitive material is in the form of a discontinuous layer defined by a substantially uniform distribution of a plurality of closely spaced discrete regions. 
     
     
       2. The improvement of claim 1 in which said discrete regions are of varying widths. 
     
     
       3. The improvement of claim 1 in which said regions have an average diameter of about 1 micron to about 30 microns, the distance between carbon regions being from about 0.1 micron to about 30 microns. 
     
     
       4. The improvement of claim 3 in which about 25-75 percent of the total surface area of said layer is constituted by carbon regions having an average diameter of about 11-30 microns, the remainder having average diameters of about 1-10 microns. 
     
     
       5. A transfer sheet for use in a thermal transfer process for reproducing a thermally detectable original image, comprising a substrate and a discontinuous layer thereon in the form of a pattern of a plurality of closely spaced discrete carbon regions of thermally transferable heat-sensitive material of varying widths substantially uniformly distributed over said substrate whereby to enable transfer of said heat-sensitive material temperature correlated with the optical density of said original image. 
     
     
       6. The transfer sheet of claim 5 in which said regions have an average diameter of about 1 micron to about 30 microns, the distance between carbon regions being from about 0.1 micron to about 30 microns. 
     
     
       7. A transfer sheet for use in a thermal transfer process for reproducing a thermally detectable original image, comprising a substrate and a discontinuous layer thereon in the form of a pattern of a plurality of closely spaced discrete regions of thermally transferably heat-sensitive material of varying widths substantially uniformly distributed over said substrate whereby to enable transfer of said heat-sensitive material temperature correlated with the optical density of said original image, about 25-75 percent of the total surface area of said layer being constituted by carbon regions having an average diameter of about 11-30 microns, the remainder having average diameters of about 1-10 microns.